Electronic controlled pumping system



June 1954 D. s. SCHOVER 2,682,364

ELECTRONIC CONTROLLED PUMPING SYSTEM Filed July 11, 1946 2 Sheets-Sheet 1 INVENTOR.

o. s. SCHOVER 2,682,364

June 29, 1954 ELECTRONIC CONTROLLED PUMPING SYSTEM 2 Sheets-Sheet 2 INVENTOR. Jana/0'0! J'Gfi over BY mam.

Patented June 29, 1954 UNITED STATES ATENT OFFICE ELECTRONIC CONTROLLED PUMPING SYS ment

Application July 11, 1946, Serial No. 682,964

4 Claims.

My invention relates to vacuum pumps, and more particularly to automatic control means for pumps such as are employed to remove the gases evolved from chemical reactions and the like.

Pumps, particularly of the Toepler type, operate on the principle of alternately evacuating a pressure chamber and supplying air thereto to alternately draw gases into the pump and then to remove them therefrom. This might be done manually by turning a valve connecting a vacuum pump to the Toepler pump for evacuating the chamber, and then turning another valve to admit air to the pump chamber, and then repeating the cycle. This would make a slow and tedious operation, and would be a very cumbersome method of evacuating large containers.

Applicant with a knowledge of these problems has for an object of his invention the provision of a control system which will permit very rapid change in the operating mechanism of such pumps.

Applicant has as another object of his invention the provision of a system for automatically controlling the flow of fluid to and evacuation of the pump chamber, determined by conditions within the pump.

Applicant has as another object of his invention the provision of a system for alternately evacuating the pump chamber and supplying air thereto, and which is automatically operated in response to changing pressure conditions within the pump during its operating cycle.

Applicant has as a further object of his invention the provision of electronic means for alternately evacuating and applying pressure to a pump, and which is responsive to conditions within the pump.

Other objects and advantages of applicants invention will appear from the following specification and accompanying drawings, and the novel features thereof will be particularly pointed out in the annexed claims.

In the drawings, Fig. 1 is a schematic diagram of the circuit for actuating the valves which control the operation of the pump. Fig. 2 is a schematic of the pump and operating equipment.

Referring to the drawings, which exemplify one preferred embodiment of my invention, 5 represents a conventional transformer, ordinarily employed in power packs, with a primary winding for connection to a conventional domestic power lie or source, preferably of the 110 volt 60 cycle variety. A tapped secondary which preferably steps up the voltage to about 325 volts on each side of the tap, feeds the anodes of a double wave rectifier 6. The cathode of the rectifier is energized from a small supplementary secondary winding of about 5 volts. The cathode of the rectifier 6 and the center tap of the main secondary winding feed into the usual low pass filter for removing the ripple and smoothing out the pulsating direct current. It consists of the usual storage condensers l, 8 across the line, and the usual iron core inductance 9 in series with the line. One side of the line, preferably the negative, is grounded while the other side feeds a voltage divider l0 which is itself grounded on one side. The other side of the voltage divider Hi feeds the anodes and screens of the trigger tubes T1, T2 and the anode of the power tube H through the winding of the relay [2. Tubes T1, T2 are preferably of the 6SJ'7 type while tube II is preferably of the 6V6 type. The variable tap on voltage divider I0 is connected to cathode of tube II and thence through a resistance to a contact on the reset switch l2. The moving contact of the reset switch I2 is connected to the control and suppressor grids of tube T1 which are in turn joined together. The other stationary contact of reset switch 12 is connected to ground.

The cathodes of tubes T1 and T2 are connected together and to ground through a Y resistance network, the legs l3, l4, and I5 of which are preferably comprised of resistances of the order of 1500 ohms. The cathodes of tubes T1 and T2 are also bridged by condenser 16 and resistance ll connected in series. If desired, the condenser It may be of the order of .25 mf. and the resistance ll of the order of 1 megohm.

The control and suppressor grids of tube T2 are joined together and grounded. The plate or anode of tube T1 is connected to the screen grid of tube T2, and the plate or anode of tube T2 is connected to the screen grid of tube T1. Interposed in the B supply for tubes T1, T2 are the usual plate resistances l8 and it of appropriate size. Connected across the anode to ground circuits of tubes T1 and T2 are neon indicator lights 2H, 21, respectively, and resistors 22, 23 preferably of one megohm size. The resulting arrangement is a trigger circuit having two stable states.

The control grid of tube H is connected through resistance 24, preferably of 1 megohm size, to the anode of tube T1, and the anodes of tubes T1 and T2 are in turn connected to termi nals of mercury switches l, 4 and 2, 3, respectively, one of which terminals on each of said switches is connected to ground as indicated.

The screen grid of tube H is joined to the anode, and the heater of tube It as well as those of tubes T1 and T2, are supplied from a supplemem tal secondary winding of about 6.3 volts on transformer 5 across which is applied a pilot light 25. Power is supplied through the movable contacts of relay [2 by line which is in turn connected to the main power line that supplies transformer 5. The back contacts of relay l2 feed the winding of valve operating relay 2'! for opening and closing the valve leading to the vacuum pump to be referred to hereinafter. The front contacts of relay l2 feed the winding of valve operating relay 28 for admitting air into the system.

Referring further to the drawings, Fig. 2 shows a conventional Toepler pump. However, any other desired form of pump or other apparatus requiring a similar intermittent operation in similar form may be employed for the purpose. In this pump the chamber is designated 29. Air is fed into and removed from the chamber 29 through line 30, and this is accomplished by valves 31, 32 controlled respectively by relays 21, 28. Valve It! connects branch 33 to a conventional vacuum pump (not shown), and valve 2' 32 connects branch 34 to the atmosphere or a source of air supply. Inserted in the line is a T coupling 25 to which is connected a rubber hose or other appropriate line 35 for communicating with a tube forming a glass housing for the elements of a mercury switch. Passing through the wall of the tube for contact with the mercury therein are contacts 2, 3. Cooperating with the upper end of chamber 29 at its mouth is the elongated body portion of the pump. This body portion has a reduced extension which passes down into the chamber 29 through the mouth thereof and terminates adjacent the bottom of the chamber 29 and is submerged under the pool of mercury 43 contained in the chamber 29. An air-tight seal is thus formed around the body extension and the chamber 29 at the mouth thereof.

The body 37 also includes two bulbous portions separated by an enlarged portion housing a valve 38. Extending upwardly and outwardly from the body 31 and in communication therewith is a line 39 for evacuating gas from a container or other appropriate place where it is either stored or generated by some desired reaction. Details such as valves and other structure have been omitted since they are well known and conventional in this form of pump. Contacts I, 4 extend through walls of body 31 and line 39, respectively, for communication with mercury forced up into the line and into the body of the pump during a cycle of its operation, to provide a switch. At the upper end of the body 31 a reduced portion ll extends outwardly and downwardly and has a valve 42 manually operated for closing. Both the pump and the tube contain mercury at 53, 44, respectively. While the foregoing apparatus is preferably made of glass, it is quite obvious that such apparatus may be made of any other appropriate material.

In its operation reset switch l2 may be moved as desired. If moved momentarily to upper contact position before being returned to ground, a positive potential is applied from voltage divider ii] to control and suppressor grids of tube T1, which causes the tube to conduct, when switch I, is open. It is assumed that mercury is down in the chamber 29. Contacts I and 4 are open. Tube T1 continues to operate after the reset switch is moved to make ground contact. The operation of the tube T1 lowers the potential across its anode-to-ground circuit to the point where tube I I will not operate, since the cathode of tube H is set by the voltage divider ID at such a positive value above ground that the control grid is sufficiently negative with respect thereto to permit tube H to become inoperative. In this state relay I2 is deenergized and the rmature thereof is on back contact position. In this position winding of relay 2? is connected to the source of power through line 26 and is energized and has opened valve 3| permitting the vacuum pump to evacuate the chamber 29 and the tube 36. At this time, tube T2 is almost, if not entirely, non-operating due to the low potential on the screen grid which is tied to the anode of tube T1, which is itself at low potential since in operation. Under these conditions neon light 2| is operating since it is connected across the non-conducting tube T2.

As this action continues, pressure is lowered in the system by the action of the vacuum pump, and the mercury 44 in tube 35 rises until it completes the circuit between contacts 2 and 3. This places the anode of tube T2 and the screen grid of tube T1 at ground potential. Such action renders both tubes T1 and T2 inoperative. However, when tube T1 ceases operation, the potential on the anode of tube T1 rises and the grid of tube H in turn rises, thus permitting tube H to conduct or increase its conduction. Neon light 2| is extinguished and neon light 20 lights up.

Operation of tube ll energizes relay l2 and pulls the armatures thereof to front contact position, disconnecting relay 2'! from its source of energy, and connecting relay 28 to the source of energy through line 26. This causes valve 3| to close and valve 32 to open. The opening of valve 32 admits air to chamber 29 through branch 34 and line 30 and affects the movement of the mercury.

The closing of contacts 2, 3 may be only instantaneous, or may have an appreciable duration. The circuit may even open or close several times. However, the opening of the circuit 2, 3, due to the fall of the mercury in tube 36 due to the admission of air into the system will render tube T2 operative and tube T1 substantially inoperative. The reason for this is the action of the memory condenser l8. During the previous operation of tube T1, the flow of current through the tube T1 and resistance l3, l5 stored up a positive charge on the plate of condenser I 6 joined to the cathode of tube T1, and a negative charge on the plate of that condenser which was connected to the cathode of tube T2. This charge will tend to leak off so that when tube T1 ceased operation, this charge commenced to leak oil and when switch 2, 3 is opened, the cathode of tube T1 assumes a higher positive potential with respect to its control grid than does the cathode of tube T2. This renders tube T2 operative and keeps the potential of the anode of tube T2 low and the potential of the anode of tube T1 high. As tube T2 continues to operate, the potential of the screen of tube T1 is lowered, and it practically, if not entirely, ceases to operate. This condition keeps the potential or the anode of tube T1 relatively high, and in turn the grid of tube ll relatively high so that tube H continues to operate and relay l2 remains energized. The screen of tube T1 being tied to the anode of tube T2 which tube is operating, is maintained at a. lower potential and provides a screen effect on the tube T1. In this condition neon light 20 remains lighted.

As relay l 2 remains energized so also does relay 5. so that valve 32 remains open, and valve 31 remains closed. Air continues to enter the system through branch 3d and line to chamber 2% causing the mercury 53 to rise up through the extension it into body 3'5 ofthe pump and the mercury in tube moves down away from contact it. The mercury in body 3i continues to climb un' 1 it reaches contacts 6 and I and closes the electrical circuit between them. The closing of these contacts places a ground across the anode-cathode circuit of tube T1 and places the screen grid of tube T2 at ground potential. In like manner the control grid of tube It is placed at ground potential. Tubes T1 and T2 do not operate under these conditions and the lowering of the grid potential of tube ii to ground level causes it to cease operation in view of the potential of the cathode. This deenergizes the relay 12 so that its armatures return to back contact position, deenergizing relay 2% and energizing relay 21. Neon light ii? is extinguished and neon light 2! lights up. The foregoing action closes valve 32 and opens valve Iii changing the cycle of operation from that of admitting to that of removing air from the system.

As this action continues, chamber 29 is eX- hausted line branch and the mercury level in body til is lowered to break the circuit between contacts 5 and d. This circuit connection may be established only momentarily or it may last an appreciable length of time. However, when the circuit is broken, tube T1 starts operating and tube T2 remains substantially inoperative while tube it remains blocked or, depending upon the voltage position of the moving contact on the voltage divider Ill, operates at such a low level that it does not energize relay Ii. Neon light 2| remains lighted. Since up until the closing of switch I, ti, tube T2 had been operating, a positive charge has been built up on the plate of memory condenser [6 which joins the cathode of tube T2, and a negative charge has been built up on the plate condenser 56 which joins the cathode of tube T1. The opening of switch 5, t leaves the cathode of tube T2 at the higher positive potential with respect to its control grid than that of T1, so that tube T1 commences to operate. This keeps the grid potential of tube ii low, and it remains inoperative. The potential of the screen of tube T2 is likewise maintained at a low value and that tube does not operate.

The above condition continues until the pressure in the system is reduced to the point where the mercury in tube 36 rises to bridge contacts 2 and 3. In this way the cycle is repeated and continues over and over again as the pump is kept operating.

The effect of the above cycle of operation is to pull gas from a chamber of the container in through line 39 and pump it up through the body of the pump 3'! and out through the extension 4 I. As the mercury recedes in body 3i, gas is pulled in through line 39 and as the mercury 43 rises in body til, it is forced up through valve 38 through extension M. The control system oi this invention insures continuous operation without continuous manual control.

If the pump is stopped, the cycle may be restarted by resetting the reset switch which causes tube T1 to conduct giving a decrease in voltage of tube ii and deenergizing the relay. This insures the operation of the pumps in the manner heretofore described. The Toepler pump disclosed herein is of the conventional type. As indicated, mercury 43 in Fig. 2, is the pumping medium. Since mercury has a relatively great density, and since it would be diflicult to find a metal or other substance for use in the ball 38 which had a density greater than mercury, without selecting some of the precious metals such as gold, it will be clear that a ball 38 of steel or some other appropriate metal, will have a lower density than that oi mercury and will float thereon. As the liquid mercury rises in the tube it and passes on up through the bulbous portion 31, it will carry the ball 33 upwardly with the mercury. Thereafter, as the mercury travels back down through the valve seat, the ball 38 will be lowered into position on the valve seat. In this arrangement it is not intended that the ball 38 shall act as a check valve to prevent the flow of mercury, but will only function to limit flow of gas in one direction.

Having thus described my invention, I claim:

1. A pumping system comprising a pump having a reciprocatory liquid mercury pumping medium, a pair of switches coupled to separate circuits and responsive to the movement of mercury medium to its extreme positions in the pump for alternately opening and closing said circuits, a trigger circuit having two stable states coupled to said, circuits and disabled by them, said trigger circuit including a pair of electric discharge devices With their cathodes resistively coupled, and a capacitance bridging the resistance coupling, whereby the operation of one discharge device in one state stores a charge upon said condenser which delays its recovery until the other of said. discharge devices has become operative to change the state, and means responsive to the change of state of the trigger circuit for reversing the movement of the pump medium to actuate said pump.

2. A combination of the character described comprising a mercury pump, sets of contacts carried by the pump and opened and closed by the action of the mercury, a trigger circuit including a pair of electric discharge devices coupled through their cathodes whereby the operation of one maintains the other in inoperative condition, each set of contacts being coupled through a low impedance circuit to said discharge devices to render them inoperative when closed, a memory circuit including a capacitor coupled between the cathodes of said discharge devices whereby operation of one of said discharge devices provides a signal for delaying its recovery when they are rendered inoperative by the closing of the contacts until after the operation of the other of said discharge devices has commenced, and means coupled to and responsive to the operation of the electric discharge devices to alternately raise and lower the mercury in said pump, said last means including a vacuum source for applying a vacuum to the mercury pump for moving the mercury in one direction, and a device for applying a pressure to the mercury for moving it in the opposite direction.

3. A system of the character described comprising a pump having a reciprocating liquid conductor medium therein, an elongated tubular body portion terminatin at one end in a liquid reservoir, a check valve positioned in an intermediate portion of the body to limit gas flow to a single direction, a source of gas coupled to the body portion adjacent the reservoir, a gas outlet at the other end of the body, a pump medium switch includin contacts in communication with the body for engagement with the reciprocating liquid conductor medium to complete a circuit when the liquid level rises, electrically operated means for alternately connecting a pressure and a vacuum source to the mercury reservoir for controlling the liquid therein, a pressure responsive switch for communication with said reservoir and responsive to pressure conditions therein, a trigger circuit having its control circuits coupled to said pressure switch and said pump medium switch and responsive to the operation thereof to flip the trigger circuit, and means for coupling the output of a discharge device of said trigger circuit to the electrically operated means to alternately apply vacuum and pressure to the reservoir for reciprocating the liquid pump medium in said body portion.

4-. A system of the character described comprising a reciprocatin mercury fluid pump havin a mercury reservoir, a liquid control switch having spaced contacts for communication with the mercury of the pump as it reciprocates therein, means for couplin a pressure source and a vacuum source to the mercury reservoir for controlling the reciprocatory flow of mercury in the pump, a pressure responsive means connected to the mercury reservoir and responsive to pressure conditions therein, means for controlling the coupling means for the vacuum source and the pressure source to selectively bring them into communication with said reservoir, a trigger circuit coupled to the liquid control switch and the pressure responsive means through its control electrodes, and means for coupling the trigger circuit to the coupling control means whereby operation of the pressure responsive means and the liquid switch will flip the trigger circuit and actuate the control coupling to alternately connect the source of vacuum and the pressure source to the reservoir to alter the pressure therein and reciprocate the liquid in the pump.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,138,527 Newman Nov. 29, 1938 2,258,415 Lago Oct. '7, 1941 2,273,993 Rockwood, Jr Feb. 24, 1942 ,357,445 Baker Sept. 5, 1944 OTHER REFERENCES Ultra-High-Frequency Techniques, by Brainerd et al., D. Van Nostrand Co., Inc., 1942, pages 171-176.

Ultra-High-Frequency Techniques, by Brainerd et al., paragraph 420, Figure 435, pages 195- 197, September 1942. 

